Above the law: Egyptian police demonstrate outside the Interior Ministry, in an attempt to absolve themselves of blame for the deaths of protesters killed in their initial crackdown

After 18 long and sometimes bitter days, the Egyptian revolution finally succeeded in ousting President Hosni Mubarak from office. The protest movement had started on January 25 but really came to life three days later after Friday prayers when a groundswell of public anger led to intense battles with police around the country. The scale and ferocity of what transpired on this "day of rage" caught Egypt's ailing president off-guard. Demonstrators demanding his removal stormed police stations, prisons and government buildings, including Mubarak's National Democratic Party headquarters, and set them ablaze. The already heavy Cairo air soon filled with dark clouds of dank, viscous smoke. In the chaos that followed, Mubarak's headquarters would be allowed to burn for three days, before partially collapsing in ruins.

This was the first time unrest in Egypt had been coordinated on a national scale. After a day of defiance in which the most brutal element of Mubarak's state apparatus, the police force, came under unprecedented attack, the army was called in to restore some order to the streets. Since then tanks have become ubiquitous in central Cairo, parked across its vertiginous boulevards and along its usually bustling intersections.

Suddenly ordinary Egyptians could express themselves as never before, and everyone wanted to be heard. Across Tahrir Square wherever a journalist was spotted, large crowds gathered, all insisting on an interview. "Thank you for coming," they said, "tell everyone our story." No one would abide silence any more. Saad Rais, aged 18, ran over to me draped in an Egyptian flag. "They killed my brother," he said, holding bullet shells and tear-gas canisters in his hands. "This is what Mubarak's police did. This is why we're here. We want our rights back and we won't leave without them."

The army's presence emboldened the protesters. If Mubarak had hoped his troops might crush them, this was his greatest miscalculation. Army regiments are not like police units — they are not used to fighting their own. Before the 1989 crackdown in Tiananmen Square, local military regiments in Beijing were replaced with battalions from Inner Mongolia. The thinking was that they would be less reluctant to act than local soldiers. In Cairo, the regiments were all local and it was clear where their sympathies lay. The army consequently declined to take an active role in dispersing the crowds and later declared the protests legitimate, effectively jettisoning any hopes Mubarak might have had of military intervention in his favour.

The limits of their patience have nevertheless been frequently tested. One morning in Tahrir Square I saw a Western journalist attempting to photograph a small demonstration of about 200 men. A soldier walked over and told her not to take pictures, threatening to confiscate her camera if she did. Two protesters hurried over. "She will take our picture," they told him, dragging her into their scrum. More protesters streamed over and argued gently with the soldier before he eventually apologised to the photographer. That the balance of power should have shifted so decisively in favour of the protesters within a matter of days illuminates just how dramatically the contours of power have been recast by this popular uprising.